For over a century, incandescent light bulbs have provided a majority of electrically-generated light. However, incandescent light bulbs are generally inefficient at generating light. Indeed, a majority of the power fed into an incandescent light bulb may be converted to heat rather than light.
More recently, light emitting diodes (LEDs), or inorganic LEDs (ILEDs), have been developed. These relatively new light sources have continued development at a fairly rapid pace, with the applicability of certain semiconductor fabrication techniques leading to further increases in lumen output. Accordingly, the combination of increased lumen output with the high luminous efficacy of LEDs may one day make LEDs a preferred lighting choice in certain situations. The adoption of LEDs as a light source may be tied to improvements in various areas that are associated with: 1) cost effective techniques for integrating active materials into device packages, 2) interconnecting devices into modules; 3) managing the accumulation of heat during operation; and/or 4) spatially homogenizing light output to desired levels of chromaticity over a lifetime of a product.
Generally speaking, LEDs have several advantages over incandescent light sources, such as increased durability, longer lifetimes, and reduced energy consumption. In addition, the small nature of LEDs, their narrow spectral emission band, and low operating voltages may one day make them a preferred light source for compact, lightweight, and inexpensive lighting (for example, solid state track lighting systems).
Despite these advantages, however, LEDs also suffer from certain disadvantages. For example, the optical power per unit of an LED's étendue may be significantly lower than a UHP (ultra high performance) lamp. As is known, étendue refers to how spread out light is in a given medium over a given area and a solid angle. This difference may be up to, and sometimes over, a factor of 30. This difference may sometimes create barriers to achieving increased luminance on a target that is a given distance away from the plane of the light source. For example, a typical light source or lamp may only operate to collect 50% of the light emitted from the source.
In certain instances, the efficiency of an LED light source may be adversely affected as a result of the increasing junction temperature associated with the LED. The junction temperature can directly affect the performance and longevity of the LED. As the junction temperature rises, a significant loss of output (luminosity) can be expected. The forward-voltage of an LED may also be dependent on the junction temperature. Specifically, as the temperature rises, the forward voltage decreases. This increase, in turn, can lead to excessive current drain on other LEDs in the array. The draining may result in failure of the LED device. High temperatures can also affect the wavelength of an LED fabricated using gallium arsenide, gallium nitride or silicon carbide.
Conventional cooling systems take advantage of convection, conduction, radiation, etc. to move heat efficiently away from the heat generator. However, in the case of LEDs, there is no infrastructure for heat removal out of the back side of the light source. This may be because conventional light sources may rely on convection from the front side of the light source.
Accordingly, it will be appreciated that new techniques for improving (or better harnessing) light from LED sources are continuously sought after. For instance, it will be appreciated that it may be desirable in certain instances to improve the optical efficiency and/or collimation of light from LED light sources. It will also be appreciated, that new techniques of thermal management for LED light sources are continuously sought after.
One aspect of certain example embodiments of this invention relates to a LED light collection apparatus. This apparatus may be adapted for use, for example, in a compact LED-based track-lighting system.
In certain example embodiments, an array of DC or AC driven LEDs (that may be, for example, chip on board or chip on glass mounted with heat management features) may be provided. In certain example embodiments, a specially designed lens may be used as a collimator in conjunction with apertures (e.g., compound parabolic concentrators) formed in a glass substrate to conserve the étendue of the light source.
In certain example embodiments, non-imaging techniques may be used to tailor surfaces in order to adjust or transform light emitted from a light source (e.g., an LED light source).
In certain example embodiments, an LED may be disposed behind or in an aperture that is formed in a glass substrate. In certain example embodiments, the glass substrate provides the surface to create an array of compound parabolic concentrator (CPC) holes. In certain example embodiments, the glass substrate may be structured to house a fully packaged LED or bare die printed circuit board (PCB) with ancillary heat sinks. In certain example embodiments, a formed glass substrate may house a lens. In certain example embodiments, the glass substrate may allow another glass plate carrying a phosphor component to be remotely spaced away from the LED. In certain example embodiments the LED can be a bare die.
In certain example embodiments, a remote phosphor plate may be used with a Fresnel lens to provide increased diffusion and/or homogenization of emitted light.
In certain example embodiments, a method of making a light fixture is proved. At least one cavity is formed in a glass substrate, the at least one cavity being tapered along a depth thereof so that the at least one cavity increases in diameter or distance from a first end thereof to a second end thereof. A reflective element is disposed on a surface of the at least one cavity. A light emitting diode (LED) is located at or proximate to the first end of each said cavity so as to enable the associated reflective element to reflect at least some light emitted from the respective LED, conserving étendue of the light from the respective LED.
In certain example embodiments, a method of making a light fixture is provided. At least one cavity is formed in a glass substrate, the at least one cavity being tapered along a depth thereof so that the at least one cavity increases in diameter or distance from a first end thereof to a second end thereof. A reflective element is disposed on a surface of the at least one cavity, the reflective element being adapted to reflect at least some light from a light source locatable at or proximate to the first end of each said cavity in order to conserve étendue of the light from the light source.
In certain example embodiments, a method of making a light fixture is provided. A glass substrate having at least one cavity formed therein is provided, the at least one cavity (a) being tapered along a depth thereof so that the at least one cavity increases in diameter or distance from a first end thereof to a second end thereof and (b) having a reflective element disposed on a surface thereof. A light emitting diode (LED) is located at or proximate to the first end of each said cavity so as to enable the associated reflective element to reflect at least some light emitted from the respective LED, conserving étendue of the light from the respective LED.
In certain example embodiments, an apparatus is provided. The apparatus may include a glass substrate having a plurality of cavities formed therein, each said cavity (a) being tapered along a depth thereof so that the at least one cavity increases in diameter or distance from a first end thereof to a second end thereof, and (b) having a reflective element on a surface thereof. The apparatus may include a plurality of light emitting diodes (LEDs) at or proximate to the first end of a respective one of said cavities so as to enable the reflective element of the associated cavity to reflect at least some light emitted from the respective LED, conserving étendue of the light from the respective LED.
In certain example embodiments, a lens is provided. The lens may include: a body portion having a curved upper surface; and first and second flares on opposing sides of the body portion, the first and second flares being symmetrical about an axis of the body portion, wherein each said flare comprises first, second, and third profiles, in which: the first profile being parabolic in shape and curving away from the body portion, the second profile extending generally upwardly and inwardly from an uppermost part of the first profile, the third profile extending between an uppermost part of the second profile and an end of the curved upper surface of the body portion, and an angle is formed with respect to planes extending from the second and third profiles, the angle being approximately 20-50 degrees.
In certain example embodiments, an apparatus is provided. The apparatus may include a substrate having a plurality of cavities formed therein, each said cavity being mirror coated and having a generally parabolic shape in cross section; and a plurality of lenses respectively disposed in the plurality of cavities, each said lens comprising: a body portion having a curved upper surface; and first and second flares on opposing sides of the body portion, the first and second flares being symmetrical about an axis of the body portion, wherein each said flare comprises first, second, and third profiles, in which: the first profile curving away from the body portion and substantially matching the parabolic shape of the cavity in which the lens is disposed, the second profile extending generally upwardly and inwardly from an uppermost part of the first profile, and the third profile extending between an uppermost part of the second profile and an end of the curved upper surface of the body portion.
In certain example embodiments, a method of making a lighting fixture is provided. A plurality of lenses are provided into respective cavities formed in a glass substrate, wherein an LED is disposed at or proximate to each said cavity, wherein each said lens comprises: a body portion having a curved upper surface; and first and second flares on opposing sides of the body portion, the first and second flares being symmetrical about an axis of the body portion, wherein each said flare comprises first, second, and third profiles, in which: the first profile curving away from the body portion and substantially matching a shape of the cavity in which the lens is inserted, the second profile extending generally upwardly and inwardly from an uppermost part of the first profile, and the third profile extending between an uppermost part of the second profile and an end of the curved upper surface of the body portion.
In certain example embodiments, a method of making a lens is provided. Glass or PMMA is casted to a shape that includes: a body portion having a curved upper surface; and first and second flares on opposing sides of the body portion, the first and second flares being symmetrical about an axis of the body portion, wherein each said flare comprises first, second, and third profiles, in which: the first profile being parabolic in shape and curving away from the body portion, the second profile extending generally upwardly and inwardly from an uppermost part of the first profile, the third profile extending between an uppermost part of the second profile and an end of the curved upper surface of the body portion, and an angle is formed with respect to planes extending from the second and third profiles, the angle being approximately 20-50 degrees.
In certain example embodiments, a lens may collect, concentrate, and/or collimate light emitted from the LED.
In certain example embodiments, an apparatus is provided where the apparatus may include a first glass substrate having at least one cavity formed therein, each said cavity (a) increasing in diameter or distance from a first end thereof to a second end thereof, and (b) having a reflective surface; at least one light emitting diode (LED) at or proximate to the first end of a respective one of said cavities so as to enable the reflective surface of the associated cavity to reflect at least some light emitted from the respective LED; and a phosphor-inclusive material disposed over the at least one LED and over the first end.
In certain example embodiments, a method of making a lighting fixture is provided. At least one cavity is formed in a glass substrate, each said cavity increasing in diameter or distance from a first end thereof to a second end thereof. A reflective element is disposed on a surface of the at least one cavity. A light emitting diode (LED) is located at or proximate to the first end of each said cavity so as to enable the associated reflective element to reflect at least some light emitted from the respective LED. A phosphor-inclusive material is disposed over the first end.
In certain example embodiments, a method of making a light fixture is provided. At least one cavity is formed in a glass substrate, the at least one cavity being tapered along a depth thereof so that the at least one cavity increases in diameter or distance from a first end thereof to a second end thereof. A reflective element is disposed on a surface of the at least one cavity, the reflective element being adapted to reflect at least some light from a light source locatable at or proximate to the first end of each said cavity in order to conserve étendue of the light from the light source. A collimating lens is disposed within each said cavity, the reflected light exiting the second end of each said cavity is substantially collimated so as to allow for 10-30 degrees of distribution. A phosphor-inclusive material is disposed over the first end.
In certain example embodiments, a lighting system may be provided that includes the apparatus. In certain example embodiments, a lighting system may be provided with a plurality of interconnected apparatuses.
In certain example embodiments, there is provided a phosphor assembly adapted for use with a lighting apparatus that includes at least one light source, the assembly, moving away from the light source, comprising: a first glass substrate; a first index layer; a phosphor component; a second index layer; and a second glass substrate. Emitted light from the at least one light source is partially refracted between the first and second index layers such that at least some of the emitted light passes multiple times through the phosphor component. The indices of refraction for the first and second index layers substantially match one another and are selected in dependence of the phosphor component material.
In certain example embodiments, there is provided an apparatus that includes a tile. The tile includes at least a first glass substrate having at least one cavity formed therein, each said cavity (a) increasing in diameter or distance from a first end thereof to a second end thereof, and (b) having a reflective surface. The tile also may include at least one light emitting diode (LED) at or proximate to the first end of a respective one of said cavities so as to enable the reflective surface of the associated cavity to reflect at least some light emitted from the respective LED. The tile further may include an active thermal management system or layer disposed proximate to the at least one LED, such that the LED is between the active thermal management system or layer and the second end, the active thermal management system or layer being configured to variably transfer heat from a first side of the active thermal management system or layer to a second side of the active thermal management system or layer, the first side being closer to the at least one LED than the second side. A thermal controller may be coupled to the active thermal management system or layer, with the thermal controller being configured to sense a temperature associated with the at least one LED and/or the active thermal management system or layer, and to control the variably transferred heat of the respective active thermal management system or layer based the sensed temperature control.
In certain example embodiments, the apparatus of claim comprises a plurality of the tiles, wherein tiles in the plurality are interconnected. In certain example embodiments, the temperature controller may be adapted to control the flow of heat proximate to some or all of the LEDs, tiles, and/or the active heat system.
In certain example embodiments, a method of making a light fixture is provided. At least one cavity is formed in a glass substrate, each said cavity increasing in diameter or distance from a first end thereof to a second end thereof. A reflective element is disposed on a surface of the at least one cavity. A light emitting diode (LED) is located at or proximate to the first end of each said cavity so as to enable the associated reflective element to reflect at least some light emitted from the respective LED. An active thermal management system or layer is disposed proximate to each one of the located LEDs, where the respective LED is between the active thermal management system or layer and the first end, the active thermal management system or layer being configured to variably transfer heat from a first side of the active thermal management system or layer to a second side of the active thermal management system or layer, the first side being closer to the respective LED than the second side. A thermal controller is coupled to at least the active thermal management systems or layers, the thermal controller being configured to sense a temperature associated with the at least one LED and/or the active thermal management system or layer, and to control the variably transferred heat based the sensed temperature control.
The features, aspects, advantages, and example embodiments described herein may be combined in any suitable combination or sub-combination to realize yet further embodiments.